Grease cleaning with liquid detergents poses an ongoing problem for consumers. Consumers utilizing liquid detergent as a light-duty liquid dishwashing detergent composition tend to wash greasy, difficult to clean items at the end of their washing experience, after easier to clean items such as glasses and flatware are cleaned. Light-duty liquid dishwashing detergent compositions require a high suds profile while providing grease cleaning.
It has been surprisingly found that the method of the present invention is highly efficient in removing grease and in particular the more difficult baked-on grease layer. Without wishing to be bound by theory, it is believed that this baked-on grease is characterized by a higher hydrophobicity. The removal of such baked-on grease therefore requires surfactants with strong hydrophobic properties in order to penetrate and fluidify efficiently the grease layer and/or requires very high level of total surfactants.
However, the use of significant levels of such highly hydrophobic surfactants presents the disadvantages of acting as soil itself and hence of monopolizing the other surfactants of the composition. Thereby, it reduces the efficiency of the composition on the basic regular grease cleaning. It has also been found that the introduction of significant levels of hydrophobic surfactants cause phase instability and suds suppression, which limits their use in dishwashing compositions.
It has been found further that the alternative route of extreme high levels of total surfactant cause phase stability issues even if the presence of hydrophobic surfactants is minimized. High levels of total surfactant are typically found in more concentrated dishwashing liquids. It has been found that the addition of the amphiphilic graft polymer of the present invention allows that total surfactant level to be maintained or even reduced whilst still maintaining or even improving grease performance.
Furthermore, it has been found that the amphiphilic graft polymer of the present invention improves the suds profile of the light-duty liquid dishwashing detergent composition to be used in the method of the present invention. It increases suds mileage, especially in soft water.
Therefore, the present invention teaches a method of washing dishes with a liquid detergent composition comprising a specific amphiphilic graft polymer.